I have not been able to find any peer reviewed clnical trials comparing electrolyte tablets combinded with water versus sports drinks. I would be leary of them for the same reason I am leary of salt tablets. You can get too much of a good thing. Excess electrolytes can be just as dangerous as too little electrolytes in fluid replacemnets. Most sport drinks are designed to get the optimum amount of electolytes to water dilution. Your method of alternating water with a sport drink may be benificial if you are drinking at a rate of 1 1/2 to 2 quarts an hour. The benefit is that you will decrease abdominal cramping from too much sugar in your intestins if you are drinking nothing but full strength sport drink. At drinking rates of less than 1 1/2 quarts per hour, your stomach should be able to handle the full strenght electrolyte solution.

There also needs to be considered in how much you drink per hour how much you sweat. Conditioned athletes can sweat up to 2 quarts per hour when working out in hot environments. You can assess whether or not you are drinking enough by weighing yourself before your workout and again in the same clothes immediately after the workout. For every 1/2 pound of weight you are down post work out you need to add an aditional 1 cup (250cc) of fluid replacement during your work out.